Lots of people, but three are emblematic:
Long time ago: My childhood best friend was a couple years younger than me. When I "grew up" and my interests changed, they didn't follow, and we drifted apart. More like I drifted away. It was also made weird when they kissed me. Had I actually "grown up" and become sentimental sooner than I did, I would have re-connected with them as an adult, but that didn't happen in time. My friend died when they were forty.
Some time ago: My adult best friend did the reverse. It was they who drifted away. Took a while for me to realize, but eventually it became clear even to me. I was the only one initiating contact.
Recently: Met someone and they started calling me a great friend before I realized we were friends at all. I never understood it, but sure, I wanted to be friends. Wanted to believe their words rather than their (lack of) action. But now I don't see them anymore, they are avoiding me on facebook, ghosting me in text, and refusing to talk to me on the phone. Effectively out of my life.